1. Field
One or more example embodiments relate to a wireless charging apparatus using a three-dimensional charging zone and, more particularly, an apparatus for constructing a wireless charging environment to improve an efficiency of wireless charging performed by an electronic device.
2. Description of Related Art
With increases of users using portable smartphones, the smartphones have been developed to provide various functions such as an Internet browser, a camera, and an application to satisfy various desires of the users.
Functions may be provided as various applications for user conveniences. When a user executes the functions in the smartphone, a battery included in the smartphone may be discharged. Thus, the user may charge the battery to continuously use the function in the smartphone. In general, the user may use an adapter connected to a charging terminal of the smartphone to charge the battery. Recently, according to a commercialization of wireless charging technology for charging a battery in lieu of using an adapter for charging the battery, the user may conveniently charge the battery without need to use the adapter.
The wireless charging technology may be technology for charging a battery of a smartphone using a transmitting resonator and a receiving resonator included in each of the smartphone and a wireless charging apparatus. The transmitting resonator and the receiving resonator may operate in a wireless a small electronic device such as a smartphone and a wireless charging apparatus. Thus, sizes of the transmitting resonator and the receiving resonator may be reduced such that the transmitting resonator and the receiving resonator are provided in sufficiently small sizes.
The reduced sizes of the transmitting resonator and the receiving resonator have allowed the transmitting resonator and the receiving resonator to be readily installed in the smartphone and the wireless charging apparatus. However, according to decreases in the sizes of transmitting resonator and the receiving resonator, a transmission distance through which a current flows may also be reduced and thus, the transmitting resonator and the receiving resonator may be used under a condition of spatial restrictions in practice. When a diameter of a receiving resonator is D, it is difficult to design and manufacture the receiving resonator that provides a transmission distance of at least 80% radio frequency (RF) efficiency at a level corresponding to the diameter of the receiving diameter simultaneously with realize the receiving resonator in a sufficiently small size. Also, even if it is possible to develop such resonator, a transmission distance of the resonator may be limited to a diameter of the resonator.
To solve this, magnetic resonance-based wireless charging technology has been suggested. In general, the magnetic resonance-based wireless charging technology may have a characteristic of medium-range transmission performed in about one meter and a diameter of a resonator may correspond to a maximum transmission distance. Thus, there has been an effort to expand the transmission distance.
In addition to the aforementioned issue, a transmission distance limit may exist in a magnetic resonance method based on a combination of resonance modes. In view of most of research results, papers, and patent of related arts, a diameter of a resonator may be recognized as a most practical transmission distance in general. As another condition, the wireless power transmission may be available in only a predetermined area including a transmitting resonator.
Also, despite an equal transmission distance, an efficiency may vary based on a distance between the transmitting resonator and the receiving resonator and the efficiency may be susceptible to a direction. For example, when the transmitting resonator and the receiving resonator are disposed to face each other, the efficiency may be maintained to be maximized. In contrast, when the receiving resonator is disposed at angle of 45° or 90°, the efficiency may significantly decrease.
Accordingly, there is a desire for a method of efficiently transmitting wireless power based on transmission distance and direction of a wireless charging.